Duplex steel: piav qhia, specifications thiab nta

2024 Tus sau: Howard Calhoun | [email protected]. Kawg hloov kho: 2023-12-17 10:28

Hnub no, cov hlau duplex tau txais ntau thiab nrov dua. Xyaum txhua lub tuam txhab nyob rau hauv lub tshav pob ntawm metallurgy yog koom nyob rau hauv zus tau tej cov hom ntawm stainless hlau. Koj tuaj yeem nyeem ntxiv txog dab tsi duplex steel yog dab tsi thiab nws muaj txiaj ntsig zoo li cas hauv kab lus no.

cov ntaub ntawv dav dav

Duplex steel tau lees paub thoob plaws ntiaj teb. Nws muaj tus yam ntxwv li cas? Ua ntej, lub zog siab ntawm cov khoom siv no tso cai rau txo qhov hnyav kawg ntawm txhua yam khoom. Secondly, nws yog nto moo rau nws loj heev tsis kam mus corrosion. Qhov no yog qhov tshwj xeeb tshaj yog pom thaum xav txog kev ntxhov siab corrosion cracking kuj.

Nws tsim nyog hais tias tam sim no cov khoom siv raw tseem tsis tau paub txog cov neeg tsim khoom, thiab yog li ntawd txhua txhua ob peb xyoos cov rooj sib tham tau tuav ntawm cov khoom siv tau txiav txim siab txog txhua yam ntawm cov hlau duplex. Txog tam sim no, txawm tias muaj kev txaus siab ntau rau cov khoom lag luam no, kev sib koom ua lag luam thoob ntiaj teb tsuas yog 1-3%.

History of tshwm sim

Tseem tsim nyog muab lub tswv yim tsimduplex steel tau yug los nyob rau hauv 1920. Tab sis thawj cov ntaub ntawv tsuas yog tshwm sim hauv 1930 hauv Sweden. Kev nthuav dav dav thiab siv cov khoom siv raw li no tau pib tsuas yog xyoo kaum xyoo dhau los. Lub ntsiab yog vim li cas rau qhov no yog nyob rau hauv lub fact tias nyob rau hauv lub xyoo no cov khoom siv technology tau zoo heev txhim kho. Tshwj xeeb, cov neeg tsim khoom tau tswj hwm lawv cov ntsiab lus nitrogen ntau dua.

Yuav kom nkag siab txog cov txiaj ntsig thiab vim li cas duplex stainless hlau tau yug los, koj yuav tsum nkag siab lwm yam tseem ceeb.

Austenitic alloys, uas yog AISI 304 lossis 08X18H10, nrog rau AISI 430 lossis 12X17 ferritic qib, yooj yim heev rau kev tsim khoom. Raws li lawv lub npe implies, lawv muaj feem ntau ntawm austenite los yog ferrite. Txawm hais tias siv dav, lawv muaj kev tsis txaus.

Disadvantages of tsoos steels

Yog tias peb tham txog austenitic steels, ces qhov tsis zoo muaj xws li tsis muaj zog, nrog rau qhov tsis muaj zog rau kev ntxhov siab corrosion tawg. Raws li rau cov khoom siv ferritic, nws lub zog yog me ntsis siab dua, tab sis tseem "tsis ncav cuag" qhov zoo tagnrho. Tsis tas li ntawd, qhov weldability ntawm steel deteriorates zoo heev nrog nce cov khoom thickness, thiab ua nkig heev ntawm qhov kub thiab txias.

Lwm qhov teeb meem me me ntawm austenitic alloy yog cov ntsiab lus npib tsib xee hauv qhov muaj pes tsawg leeg. Qhov no ua rau tus nqi siab dua ntawm cov khoom, uas, ntawm chav kawm, tsis muaj cov neeg siv khoom txaus siab rau.

Duplex txiaj ntsig

Lub tswv yim ntawm kev tsim duplex stainless hlau los ntawm kev xav kom sib npaug ntawm ferritic thiab austenitic hauv paus kom tau txais cov khoom tshiab, zoo dua. Kwv yees li ntawm tib tus nqi ntawm ferritic thiab austenitic steel ua rau cov txiaj ntsig hauv qab no:

• Lub zog loj. Lub zog tawm ntawm 0.2% yuav yog 400 txog 450 MPa, uas yog 150 txog 200 MPa ntau dua tuaj yeem pom nrog austenitic lossis ferritic alloys. Qhov no coj mus rau qhov tseeb tias nws muaj peev xwm txo tau cov thickness ntawm cov khoom, thaum tsis poob lub zog. Thiab qhov txo qis hauv thickness ua rau txo qis hauv qhov kawg loj. Qhov no yog ib qho tseem ceeb heev nyob rau hauv lub tshav pob ntawm lub tsev, tso tsheb hlau luam thiab siab hlab ntsha.
• Dab tsi yog qhov zoo ntawm cov hlau duplex dua li lub zog? Lub weldability ntawm cov hlau yog zoo heev txawm nrog loj thicknesses.
• muaj zog cuam tshuam. Zoo tshaj ferritic alloys. Qhov no yog qhov tseeb tshwj xeeb tshaj yog thaum huab cua kub ib puag ncig poob rau -50, thiab qee zaum mus rau -80 degrees Celsius.
• High resistance to stress corrosion cracking. Cov ntaub ntawv Austenitic yog qhov ua rau muaj qhov tsis xws luag. Qhov kev ntsuas no ua lub luag haujlwm tseem ceeb hauv kev lag luam xws li brewing tanks, concentrators, pas dej ua ke.
• Duplex steel boilers muaj kev ntseeg ntau dua li austenite boilers.

Kev sib tw

Tam sim no tsis tu ncuasteel yog raug rau xws li qhov tsis xws li corrosion cracking los yog SCC - Stress Corrosion Cracking. Hom corrosion no feem ntau tshwm sim nyob rau hauv qee yam mob. Tus neeg sawv cev ua rau tuaj yeem yog qhov muaj zog tensile kev nyuaj siab, siab kub (50 degrees Celsius saum xoom). Thiab yog tias peb tham txog cov pas dej da dej, tom qab ntawd vim qhov raug dej tas li, hom kev xeb tuaj yeem tshwm sim txawm tias ntawm 25 degrees.

Austenitic steel qib tau cuam tshuam los ntawm qhov tsis xws luag. Ib qho ferritic alloy muaj kev ntseeg siab dua hauv qhov no, nrog rau duplex stainless hlau a890 3a raws li ASTM thiab lwm qib. Lub siab coefficient ntawm kev ua haujlwm tso cai rau cov khoom siv no siv rau hauv kev tsim cov dej rhaub dej, brewing tank, desalination nroj tsuag. Qhov ntawd yog, qhov uas muaj qhov kub thiab txias thiab tiv nrog kua.

Nws yog txwv tsis pub ua pas dej ua ke los ntawm cov hlau austenitic zoo tib yam vim qhov tsis xws luag. Yav dhau los, nws yog ib qho tsim nyog yuav tsum tau siv cov hlau alloy nrog cov ntsiab lus nickel siab heev, uas ua rau kom nce tus nqi ntawm cov khoom. Niaj hnub no, duplex lossis super duplex steel siv tau.

"Super" thiab "Hyper" duplex khoom

Nws tsim nyog hais tias yog tias koj ntxiv nickel rau ferritic chromium hlau, koj tuaj yeem tau txais cov qauv sib xyaw. Ntawd yog, nws yuav muaj ob qho tib si austenite thiab ferrite. Raws li nws tau dhau los ua qhov tseeb, nws yog qhov tseeb xws li kev sib xyaw uas tau pib hu ua cov khoom siv duplex. Cov prefixes "super" lossis "hyper" duplex steel qhia tias cov khoom siv raw muaj qhov nce ntxivtus nqi ntawm alloying Cheebtsam. Qhov no qhia tau tias muaj kev tiv thaiv corrosion ntau dua li cov khoom siv.

"Super" thiab "hyper" duplex steel yog siv heev hauv cov khoom siv roj. Tsis tas li ntawd, cov khoom siv raw yog siv rau hauv cov khoom noj, tshuaj, kev tsim kho thiab kev lag luam kev kho mob.

vuam khoom

Txawm hais tias qhov zoo weldability ntawm cov khoom no, qee cov cai yuav tsum tau ua. Ua ntej pib vuam, xyuam xim rau cov hauv qab no:

• kom paub meej qhov zoo ntawm kev nkag mus ntawm cov khoom siv, qhov sib txawv ntawm lub hauv paus ntawm kev sib koom tes thiab lub kaum sab xis ntawm kev txiav cov npoo yuav tsum tau ua kom loj dua me ntsis rau cov hlau zoo tib yam;
• qhov sib koom ua ke, nrog rau cov hlau nyob ib puag ncig ntawm qhov chaw no, tau pom zoo kom ntxuav kom huv si ntawm txhua qhov kev sib kis;
• tsuas yog txhuam ua los ntawm cov hlau hlau nrog kev tiv thaiv corrosion;
• vuam electrode yuav tsum qhuav.

Thaum vuam duplex steel, ua raws li cov cai no:

• Nws yog ib qho tseem ceeb heev uas yuav tsum tau saib xyuas xws li qhov ntsuas qhov ntsuas kub. Nws yuav tsum tsis txhob qis heev los yog, conversely, siab dhau. Rau cov hlau duplex zoo tib yam, qhov sib txawv ntawm 0.5-2.5 kJ / mm yuav tsum tau ua raws li lub sijhawm vuam. Tsis tas li ntawd, qhov kub ntawm qhov sib cuam tshuam yuav tsum tsis pub tshaj 200 degrees Celsius.
• Tsis muaj dross yuav tsum tshwm rau tom qab ntawm qhov vuam. Ntawm no nws yog ib qho tseem ceeb heev los xaiv cov roj zoo uas yuav tiv thaiv lub hauv paus ntawm cov seam. Feem ntau siv roj sib tov rau kev tiv thaiv yog high-purity argon thiab hydrogen los yog nitrogen.
• vuam yuav tsum tsuas yog ua los ntawm tus neeg muaj peev xwm. Qhov no yog vim qhov tseeb tias nyob rau hauv qhov chaw kub hnyiab, cov hlau yuav ua rau muaj kev nyiam rau corrosion, thiab kuj tseem muaj qhov tshwm sim ntawm kev tawg.
• Thaum lub sij hawm vuam, tsis txhob ua kom dav transverse vibrations ntawm lub electrode. Qhov no tuaj yeem ua rau muaj cua sov ntau dhau, uas yuav ua txhaum txoj cai.

Ua haujlwm tom qab vuam

Muaj qee cov lus qhia ua raws tom qab vuam.

• Txhawm rau kom muaj kev tiv thaiv corrosion siab ntawm cov hlau vuam, nws yuav tsum tau ntxuav kom huv. Nws yog ib qho tsim nyog kom tshem tawm cov oxide zaj duab xis thiab tshem tawm tag nrho cov seem ntawm slag.
• Txhuam txhuam ua haujlwm tsuas yog ua los ntawm tes thiab tsuas yog nrog cov txhuam hlau nrog cov khoom tiv thaiv corrosion. Yog tias siv cov cuab yeej siv tshuab, qhov no tuaj yeem ua rau micro-kua kua muag hauv cheeb tsam seam, uas yuav txo nws lub zog.
• Feem ntau, tsis muaj kev kho cua sov ntawm cov seam tom qab vuam yog xav tau.

Cov khoom tsis txaus

Txawm hais tias muaj kev sib kis ntawm cov khoom siv thiab nws zoo li pom tseeb thiab qhov txiaj ntsig tseem ceeb, nws tseem tsis tau txais kev lees paub thoob ntiaj teb thiab, feem ntau yuav, yuav tsis ua tus thawj coj hauv khw. Qhov no yog vim muaj ntau yam tsis zoo,uas tsim nyog paub. Vim yog lawv, xws li cov hlau yuav ib txwm yog "niche".

Tam sim ntawd nws tsim nyog pib nrog lub zog siab ntawm cov khoom. Nws yuav zoo li qhov txiaj ntsig tseem ceeb, tab sis nws dhau los ua qhov tsis zoo loj thaum nws tsim nyog los ua cov hlau los ntawm kev siv tshuab los yog lub siab. Lwm qhov tsis zoo ntawm lub zog siab yog qhov txo qis hauv qhov muaj peev xwm ntawm cov yas deformation. Vim li no, cov ntaub ntawv duplex tsis yog qhov tsim nyog rau kev tsim cov khoom lag luam uas yuav tsum muaj cov ductility siab.

Txawm hais tias cov yas, nws yuav zoo li, yog nyob rau hauv ib qho kev txaus siab rau kev ua hauj lwm, koj tseem yuav tau siv zog heev. Vim li no, duplex steels thiab alloys rau roj thiab roj fittings tsis tau siv dav.

Qhov tsis zoo tom ntej yog qhov kev siv thev naus laus zis zoo ntawm smelting duplex stainless hlau. Austenitic thiab ferritic khoom yog yooj yim dua rau yaj. Yog tias cov cuab yeej tsim khoom raug ua txhaum cai, tshwj xeeb tshaj yog thaum cov txheej txheem kev kho cua sov, lwm cov theem yuav tsim nyob rau hauv cov khoom ntxiv rau austenite thiab ferrite, uas yog undesirable kiag li. Feem ntau, sigma theem lossis 475-degree brittleness tshwm sim.

Tsis xav tau theem hauv cov ntaub ntawv raw

Sigma theem yog tsim nyob rau hauv xws li cov khoom ntawm 1000 degrees Celsius thiab siab dua. Feem ntau, cov ntsuas kub no tshwm sim yog tias cov txheej txheem txias tom qab vuam lossis thaum lub sijhawm tsim khoom tsis nrawm txaus. Tsis tas li ntawd, cov ntsiab lus alloying ntau yuav muaj nyob rau hauvmuaj pes tsawg leeg, qhov ntau dua qhov tshwm sim ntawm cov tsos ntawm xws li ib theem. Hauv lwm lo lus, tsim super duplex lossis hyper duplex steel yog qhov nyuaj heev.

Raws li 475-degree brittleness, nws tshwm nyob rau hauv cov ntaub ntawv ntawm kev tsim ntawm ib theem hu ua alpha-stroke. Raws li lub npe qhia, qhov kub txaus ntshai tshaj plaws yog 475 degrees Celsius, tab sis qhov teeb meem kuj tuaj yeem tshwm sim ntawm qhov qis dua, kwv yees li 300 degrees. Vim li no, kev txwv qhov kub siab tshaj plaws yog txwv rau kev siv cov khoom los ntawm cov khoom siv raw li no. Lawm, vim qhov no, qhov dav ntawm cov hlau tau nqaim ntau dua.

Raws li tag nrho cov saum toj no, peb tuaj yeem ua qhov xaus li ntawd. Duplex steel qib yog ib qho kev daws teeb meem zoo thiab hloov cov ntaub ntawv txheem, tab sis nyob rau hauv qhov nqaim heev.

Results

Duplex alloy yog siv tsawg dua li lwm hom hlau. Txawm li cas los xij, nws nrov hauv qee qhov chaw. Feem ntau nws yog siv nyob rau hauv petrochemical teb, automotive kev lag luam thiab nyob rau hauv zus tau tej cov pas dej ua ke. Weldability zoo heev, corrosion kuj thiab siab hnav tsis kam ua rau cov khoom siv no nrhiav tau tiag tiag rau ntau yam.